pr_set_error() doesn't apply to endpoints defined inside pr_mount()

[gacolitti]

I expect pr_set_error() to be invoked when hitting endpoints defined inside pr_mount():

library(plumber)

pr1 <- pr() |> 
  pr_get("/error", function() log("a"))  

pr() |>
  pr_mount("/get", pr1) |>
  pr_set_error(function(req, res, err) {
    browser()
  }) |>
  pr_run()

In this example, the handler function inside pr_set_error() is never invoked when hitting the /get/error endpoint.